The present invention relates to knives for shredders.
With reference to FIGS. 1-3, a shredder 10 known in the prior art includes a rotating drum 14 located near the bottom of a hopper 18. Knives 22 are mounted to the drum 14 on knife holders 26, and as the drum 14 rotates, the knives 22 cut against a stationary bed knife 30 mounted to the hopper 18. Material (e.g., carpet) is fed into the hopper 18 and the material is cut as it passes between the drum 14 and the bed knife 30. With reference to FIG. 3, the knives 22 include a central threaded bore 34 for a fastener 36 to attach the knives 22 to the knife holders 26. When installed, the corners of the knives 22 and the corresponding bed knife 30 act as the primary cutting surfaces. Once a corner of the knife 22 is worn, the knife 22 is removed, rotated and re-installed with a different corner acting as the primary cutting surface. The knives 22 are an all steel body and need to be replaced often due to excessive wear. Alternatively, with reference to FIGS. 4A-4B, cutting tips 38, known in the prior art, can be added to the corners of knife bodies 42, 46 to improve the operating life of knives 50, 54. The cutting tips 38 are typically made of harder material than the knife bodies 42, 46 (e.g., carbides). However, the cutting tips 38 themselves, and more specifically the bond between the cutting tips 38 and the knife bodies 42, 46, are subject to failure. Sometimes fasteners 56 are used to secure the cutting tips 38 to the knife bodies 42 (FIG. 4A). Alternatively, the cutting tips 38 have been individually brazed to the knife bodies 46 (FIG. 4B). The knives 50 and 54 include discontinuities between the tips 38 and the knife bodies 42, 46. The discontinuities result in less effective cutting surfaces, subjected to increased wear and shortened operational life.